Besremi increase in HCT

[Cityreach]

Hi

I have PV my target is 0.43 as this is best for me, I changed to Besremi from Peg in DEC24 and over my last 2 visits Jan & Mar 25 since on Besremi some of my bloods are climbing HCT yesterday was 44.6 hence a venesection was required also my HB had climbed to 148 which is top of range for Guys, I am normally around HCT 39-40 and HB 120-130, everything else is ok with not much change since start of Besremi and all in range platlets are 189 which is pretty normal for me, am I worrying unnecessarily at the moment, I have been asked to increase Besremi from 60 to 100 fortnightly which I know is still quite a low dose, anyone else had a climb in any bloods since switching to Besremi

[hunter5582]

It is not surprising that your HCT climbed a bit on such a low dose of Besremi. I do not know what your PEG dose was but the conversion formula is as follows.

Sum of monthly PEG dose x 0.7/2 = biweekly BES dose.

90mcg PEG weekly = 126mcg BES q 14 days

45mcg PEG weekly = 63mcg BES q 14 days

Note that these are just estimates that provide a starting point. Dose titration would almost always be needed as you figure out your own individual reaction to Besremi.

I started on 100mcg BES when I switched from 54mcg PEG. I was about to need to up the PEG dose so I started a bit higher on BES. I chose to raise the BES dose in 25mcg increments rather than the recommended 50mcg. I have maxed my dose at 175mcg due to mild lymphopenia / borderline neutropenia and elevation in LFTs. I also experience thrombocytosis with the PV and this dose of BES controls that. I do seem to need a venesection about once per year.

I suspect you do not have much to worry about. Needing dose titration is the norm when switching medications. Whenever I am in this situation, we monitor CBC/CMP every two weeks until we reach stability. In your situation, I would keep an eye on your PLT level as you would not want it to drop too low. Your MPN care team at Guys can work with you to set an acceptable goal for PLTs.

All the best.

[Cityreach in reply to hunter5582]

Thanks Hunter, I was only on Peg at 45mcg weekly they converted that to 63mcg fortnightly for Besremi although was told to do 60 as you cannot quite get 63, will see how I go then, my platlets have varied always around 176-189 since April 24 this was when I went from Peg 45mcg fortnightly to Peg 45 weekly then they always stayed roughly the same and have stayed the same once I switched to Besremi too, would your thoughts be this is bit too low then

[hunter5582 in reply to Cityreach]

While the PEG q 7 days 45mcg conversion is to BES 63mcg q 14 days, this is just an estimate. The dose you will need is based on your actual response. If you are not staying at your HCT/HGB target at the current dose, then you likely need a higher dose. It is always a balancing act with these meds. We have to keep multiple factors in a certain range. We all respond differently to each of the meds. Sometimes we just have to work with our care team to find the optimal dose.

Suggest you review the plan with your MPN care team regarding both dosing and the hematologic targets. You need to find the Goldilocks zone for all hematologic parameters. Not too high - Not too low. And watch for any adverse effects like LFT elevation.

Wishing you success moving forward. Please do let us know what your care team recommends and how you get on.

[Cityreach in reply to hunter5582]

Thanks Hunter fr your time and expertise, wish you well too

[Ovidess]

Cityreach, I've been on Besremi for quite a while, and am now down to 50 mcg/month to avoid side effects. The medicine controls my HCT very well, in fact, I keep asking the doctor is perhaps I have ET not PV. However my platelets, which finally dipped into normal for a few months, are rising very slowly each month now. How different we all are, huh?

[Cityreach in reply to Ovidess]

Hi Ovidess

Yes it's strange how it affects us all differently even though we have the same disease, side effects from meds are always a concern for me too and I really like to keep as low as possible if it's working, strangley platelets have never been an issue for me, it's been hematocrit and hemoglobin mainly, I wish you well going forward

[Mamabear2222]

Thank you